The invention relates to a device for setting the length of a top link of a tractor attaching device. The attaching device, apart from a top link, also includes two lower steering arms. The two lower steering arms are arranged so as to be laterally displaced from the longitudinal axis of the tractor and are articulatably attached at one end. The top link has a power drive which is used for length setting.
A publication entitled "Hydraulic Top Link with Hook" of GKN Walterscheid GmbH, Lohmar, Germany (TAS 156/ID/GB/F 996 G10-I309562) describes a top link with a hydraulic cylinder used as a power drive. It has a double-acting piston-cylinder unit with a twin return valve (double check valve). The valve serves to block the set length even in the case of longer periods of rest. A marking rod is also provided, which facilitates handling.
Achieving the optimum length setting for the top link when the tractor operates with an attached implement requires considerable experience. The operative always has to carry out a manual operation to adapt the length setting. This is labor-intensive and optimum kinematic conditions for the respective implement are not achieved.